SMA resin formulation

ABSTRACT

Resin compositions including at least two different inert fillers that are useful for preparing prepregs and laminates that are used in manufacturing printed circuit boards.

This application is a continuation of U.S. patent application Ser. No.16/320,282, filed Jan. 24, 2019, now U.S. Pat. No. 11,365,282, which isa national stage application under 35 U.S.C. § 371 of InternationalApplication No. PCT/US2017/043633, filed Jul. 25, 2017, which claimspriority to U.S. Patent Application No. 62/366,115, filed Jul. 25, 2016,the disclosures of which are explicitly incorporated by referenceherein.

(1) FIELD OF THE INVENTION

This invention relates to resin compositions used to impregnate wovenmaterials that are then partially or fully cured to form prepreg andlaminate sheets that are used to manufacture printed circuit boards. Theprepregs and laminates that are prepared using the resin compositions ofthis invention possess excellent electrical performance suitable forhigh frequency application in electronics, as well as excellent thermaland mechanical performance.

(2) BACKGROUND OF THE INVENTION

Fillers such as talc can be important ingredients in resins used tomanufacture prepregs and laminates that are subsequently used in printedcircuit board manufacturing. Talc provides thermal stability, fillsvoids and improves PCB drilling. Styrene maleic anhydride (SMA) is aningredient of certain resins used to prepare prepregs and laminates. SMAcan be included in resins to improve glass transition temperatures (Tg).Talc and SMA, when used together in a resin system for PCB applicationscan provide prepregs with improved thermal reliability under reflow.However, with ever changing thermal and electrical specifications forlaminates and printed circuit boards, there remains a need for prepregsand laminates with improved thermal, electrical and mechanicalproperties.

SUMMARY OF THE INVENTION

Laminates and prepregs used in printed circuit boards are formed intolayups and ultimately into printed circuit boards (PCBs) that includemultiple laminate layers that are bonded together. One problem thatarises with PCBs is that adjacent laminate layers can delaminateespecially when the layups or PCBs are subjected to elevatedtemperatures. Delamination can cause board failure. Additionally, PCBmanufacturers are also starting to demand prepreg materials that can beused to manufacture PCB that exhibit low wicking and white glasscharacteristics. Therefore, there is a need for prepregs, laminates,resin coated copper and like resin containing materials that are usefulin forming PCBs that are less prone to delamination and/or the exhibitimproved wicking and/or white glass characteristics.

In one aspect we have discovered that using an unexpected combination offillers—silica and talc—provides a synergistic combination that improvescertain laminate and/or PCB electrical and/or thermal properties morethat using either silica or talc alone. This is especially the case withan anhydride curing agent used.

Another aspect is a resin composition comprising styrene maleicanhydride co-polymer; at least one epoxy resin; at least onecross-linking agent; talc; and silica.

Still another aspect is a resin composition comprising: from about 5 toabout 40 wt % on a dry solvent free resin basis of a styrene maleicanhydride co-polymer; from about 10 to about 50 wt % on a dry solventfree resin basis of at least one epoxy resin is selected from abrominated bisphenol A, a brominated bisphenol F, a non-brominatedbisphenol A, a non-brominated bisphenol F and combinations thereof; fromabout greater than 0 to about 20 wt % on a dry solvent free resin basisof at least one cross-linking agent is selected from tetrabromobisphenolA, tetra-DOPO-bisphenol A and mixtures thereof; from about 2.5 to about15 wt % on a dry resin basis of talc; and from about 2.5 to about 15 wt% on a dry resin basis of fumed silica.

Yet another aspect are prepregs and/or laminates including a reinforcingmaterial impregnated with the resins described herein as well as resincoated copper foils comprising a copper foil sheet having a first planarsurface and a second planar surface and a layer of B-staged or C-stagedresin described herein applied to at least one of the planar surfaces.

DESCRIPTION OF CURRENT EMBODIMENTS

This disclosure is directed generally to resins made from a plurality ofingredients as well as to prepregs and laminates including the partiallyor fully cured resins.

The resins are made by a “compounding” process where resin ingredientsare combined to form a thermosetting resin. The resins are used in oneexample to manufacture a laminate by “impregnating” a reinforcingmaterial such as a woven glass fabric with the resin. In anotherexample, the resin are used to coat a copper foil sheet to form aresin-coated copper laminate. In another example, the resins are used toform a laminate sheet that does include a reinforcing material. One typeof product made using the resins are “prepregs”—i.e., a sheet materialthat my include resin or a resin impregnated reinforcing material inwhich the resin in only partially cured or “B-staged”. Another type ofproduct that is made from the resins are C-staged laminates in which theresin is fully cured. The ingredients used to formulate the resins arediscussed below. Unless stated otherwise, the component weight percentranges are reported on a “dry” solvent free basis.

The resins of the invention include: (1) at least one SMA co-polymer;(2) at least one epoxy resin; (3) at least one co-crosslinking agent;(4) talc; (5) fused silica; and a catalyst. The resins can include avariety of optional ingredients including a UV blocker, flame retardantand solvents.

Copolymers of SMA

A first component of the resins of this invention is one or more SMAcopolymers. Copolymers of styrene and maleic anhydride have beendescribed, inter alia, in Encyclopedia of Polymer Science andEngineering Vol. 9 (1987), page 225. Within the framework of theinvention the term “copolymer” likewise refers to SMA or mixtures ofSMA.

Useful styrene and maleic anhydrides (SMA) are type 1 SMA copolymerswhich have a molecular weight in the range of about 1400 to about 50,000and an anhydride content of more than 15% by weight. Preference is givento SMA copolymers having a molecular weight in the range of 1400 to10,000. Examples of such copolymers include the commercially availableSMA 1000, SMA 2000, SMA 3000, and SMA 4000. These copolymers have astyrene:maleic anhydride ratios of, for example, 1:1, 2:1, 3:1, and 4:1,5:1, 6:1, 7:1; 8:1 and 9:1 respectively, and a molecular weight rangingfrom about 1400 to about 4000. Mixtures of these SMAs may also be used.

The amount of SMA copolymer employed in the resins will range from about5 to about 40 wt % on a dry solids basis and more suitably from about 5to about 30 wt %.

Epoxy Resin(s)

The term “epoxy resin” in this context refers to a curable compositionof oxirane ring-containing compounds as described in C. A. May, EpoxyResins, 2^(nd) Edition, (New York & Basle: Marcel Dekker Inc.), 1988.

Some examples of epoxy resins include: those based on the diglycidylether of bisphenol A; on polyglycidyl ethers of phenol-formaldehydenovolac or cresol-formaldehyde novolac; on the triglycidyl ether oftris(p-hydroxyphenyl)methane or on the tetraglycidyl ether oftetraphenylethane; amine types such as those based ontetraglycidyl-methylenedianiline or on the triglycidyl ether ofp-aminoglycol; cycloaliphatic types such as those based on3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate. The term“epoxy resin” also stands for reaction products of compounds containingan excess of epoxy (for instance, of the aforementioned types) andaromatic dihydroxy compounds. These compounds may be halogensubstituted.

Preference is given to epoxy resins, which are derivative of bisphenolA, particularly FR4, especially on account of their low price. FR4 ismade by an advancing reaction of an excess of bisphenol A diglycidylether with tetrabromobisphenol A. Mixtures of epoxy resins withbismaleimide resin, cyanate resin and/or bismaleimide triazine resin canalso be applied.

It should be noted that epoxy resins are generally represented by asingle, unequivocal structural formula. The skilled person will knowthat this should be taken to include deviating products resulting fromside reactions occurring during epoxy resin preparation. As these sideproducts constitute a normal component of cured epoxy resins, theylikewise constitute a normal component of the resins according to theinvention.

One or more epoxy resins are included in the resins in a total amountranging from about 5 wt % to about 50 wt % on a dry basis and morenarrowly from about 10 wt % to about 40 wt %. In one aspect of thisinvention, the resin includes two different epoxy resins.

Cross-Linking Agent(s)

The resins will include one or more cross-linking agents. Usefulcross-linking agents include brominated and non-brominated bisphenol A,brominated and non-brominated bisphenol A diglycidyl ether,tetrabromobisphenol A and tetra-DOPO-bisphenol A. As noted above, eachcross-linking agent may be optionally be brominated, i.e. substitutedwith one or more bromine atoms. Brominated co-cross-linking agents areuseful because of their flame retarding properties. Preferably, thearomatic moieties of both BPA and BPADGE are substituted with twobromine atoms each, to give tetrabromo-TBBPA and TBBPADGE, respectively.Optionally brominated novolacs can also be used as cross-linking agents.

The amount of cross-linking agent(s) used in the resins will range fromabout greater that 0 to about 20 wt % on a solvent free or solids basisand more narrowly from about 0.05 to about 10 wt %.

Fillers

The resins of this invention include two or more different fillers. Ingeneral the fillers can be selected from one or more of fused silica,amorphous fused silica, crystalline silica, fumed silica, talc, coreshell particles, Teflon®, quartz, ceramics, particulate metal oxides inamorphous or crystalline form such as silica, titanium dioxide, alumina,ceria, clay, calcined clay, boron nitride, wollastonite, particulaterubber, polyphenylene oxide and mixtures thereof. Other examples ofuseful fillers include calcined clay, fused silica and combinationsthereof.

Especially useful fillers are talc and silica with fused silica and talcbeing an especially useful combination. The first filler and secondfiller are present in the resin in an amount ranging from about 5 wt %to about 50 wt % on a dry resin basis, and more narrowly from about 5 wt% to about 37.5 wt % on a dry resin basis and finally, more narrowlyfrom about 5 wt % to about 25 wt % on a dry resin basis.

When a combination of talc and silica is used in the resin, then thetalc should be present in an amount ranging from about 2.5 wt % to about25 wt % and the silica should be present in an amount ranging from about2.5 wt % to about 25 wt %. More narrowly, the talc should be present inan amount ranging from about 2.5 wt % to about 15 wt % and the silicashould be present in an amount ranging from about 2.5 wt % to about 15wt % both on a dry resin basis. In an alternative embodiment, the weightratio of silica or fumed silica to talc in the resin will range fromabout 1:2.5 to about 5:1 and more narrowly from about 1:1 to about2.5:1.

One example of useful talc is Microtuff AGD manufactured by BarrettsMinerals, Inc. The talc can be silane treated or untreated. In addition,the average talc particle size will be less than about 1.2 microns andpreferably less than about 0.9 microns. Smaller talc particles are ableto fill resin voids in smaller amounts and as a result the resins areless prone to expansion upon heating.

One example of useful silica filler is an amorphous fused silica and inparticular and amorphous fused silica having a D₅₀ particle size lessthan about 6.0 microns and more narrowly less than 4.0. In anotherexample, the silica has percolation threshold of from 2-4 microns.Silica's having a 2-4 micron percolation ration have been found toenhance prepreg or PCB properties such as electrical properties whilesuch properties as well as mechanical properties begin to degrade whenusing silica having a percolation threshold outside of this range. Thesilica may be silated (silane treated) or non-silated (not treated withsilane). Silane treatment uses silence and silazanes to chemicallymodify the silica (or talc) surface to render the surface hydrophobic.

Flame Retardants

The compounded resins of this invention may include one or more flameretardants. Any flame retardant that is known to be useful in resincompositions used to manufacture composites and laminates use tomanufacture printed circuit boards may be used. The flame retardants maycontain halogens or they may be halogen free. Examples of useful flameretardants include, but are not limited to, halides of glycidyletherified bifunctional alcohols, halides of novolac resins such asbisphenol A, bisphenol F, polyvinylphenol or phenol, creosol,alkylphenol, catechol, and novolac resins, inorganic flame retardantssuch as antimony trioxide, red phosphorus, zirconium hydroxide, bariummetaborate, aluminum hydroxide, and magnesium hydroxide, andphosphorous-based flame retardants such as tetraphenyl phosphine,tricresyl-diphenyl phosphate, triethylphosphate,cresyldiphenyiphosphate, xylenyl-diphenyl phosphate, acid phosphateesters, ammonia phosphate, ammonia polyphosphate, ammonia cyanurate,phosphate compounds containing nitrogen, and phosphate esters containinghalides.

Phosphorous-based flame retardants may include, for example thosedisclosed in U.S. Pat. Nos. 6,645,631, 7,687,556 and 8,129,456 thespecifications of each of which is incorporated herein by reference.

Flame retardants will be present in the resin compositions of thisinvention in an amount sufficient to allow laminates made from the resincompositions to pass the UL-94 flammability test. More narrowly, theflame retardant or combinations thereof may be present in the resin inan amount ranging from about 5 wt % to about 50 wt %, or from about 10wt % to about 30 wt % on a dry weight basis.

In one preferred embodiment, the flame retardant is the solid flameretardant decabromodiphenylethane, which has the following structure:

Decabromodiphenylethane is commercially available, for example, fromAlbemarle Corporation (451 Florida St., Baton Rouge, LA 70801). TheAlbemarle product is sold as Saytex™ 8010. Decabromodiphenylethane alsounexpectedly improves the dielectric properties of the cured resincomposition. As a result, decabromodiphenylethane can be included in theresin compositions in amounts far greater than is necessary for a flameretardant in order to also enhance the dielectric properties of thecured resin. Another useful high bromine content insoluble flameretardant is ethylenebistetrabromophthalimide which is sold as SaytexBT93 W by Albemarle Corporation. Other similar useful flame retardantsinclude decabromodiphenyl oxide and brominated polystyrene.

Initiators/Catalysts

The resins will further include an initiator/catalyst the promotes thecross-linking of resin ingredients by, for example, performing a varietyof functions such as encouraging homopolymerization and/or crosslinkingresin ingredients and to be available during resin thermosetting toenhance the rate of resin cure. The initiators/catalysts chosen may beany compound that is known to be useful in resin synthesis or curingwhether or not it performs one of these functions.

On example of useful initiators are azo-type initiator/catalyst such asazobisisobutyronitrile (AIBN), 2-propyl imidiazole (2-PI),tetrabutylphophonium acid acetate (TBPAAc) and 2-methylimidazole (2-MI).

The amount of initiator used depends upon its application. When used ina resin, the initiator will be present in an amount ranging from about0.01 to about 3.0 wt % and more narrowly from about 0.05 to about 1 wt%.

In certain aspects, the resins will generally include the ingredients inamounts reported in Table 1 below where the amounts are reported inparts by weight on a solvent-free or solids only basis.

TABLE 1 Resin Formula Ingredient Wt % SMA 10-40 Epoxy resin such asbrominated or  5-40% non-brominated bisphenol A or Bisphenol Ftetrabromobisphenol A or tetra-  0-20 DOPO-bisphenol A Flame retardant 0-20 At least two fillers  5-40An alternative resin composition is summarized in Table 2 below whereingredient amounts are reported in parts by weight including solvent(s).

TABLE 2 Component Resin Formula Name Chemical Name Wt % Solvent Acetone,methyl ethyl ketone,   30-40 propyl acetate, toluene, cyclohexanone SMAStyrene maleic anhydride   15-30 copolymer Epoxy Resin Epoxy resin -brominated or    5-40 non-brominated bisphenol A or bisphenol FCross-linking Tetrabromobisphenol A or tetra-  0.5-10 AgentDOPO-bisphenol A Flame retardant    0-20 Filler 1 Fused silica  2.5-25Filler 2 Talc  2.5-12.5 UV Blocker Tinopal OB (Optional) 0.01-0.03In one aspect, this invention includes resins having the followingingredients were the weight percent amounts are reporting on a totalsolids (solvent free) basis:

-   -   1. 10-40 wt % styrene maleic anhydride copolymer (SMA);    -   2. 5-40 wt % Epoxy (a combination of brominated or        non-brominated bisphenol A or bisphenol F);    -   3. 0-20 wt % Tetrabromobisphenol A or tetra-DOPO-bisphenol A;    -   4. 5-20% halogen containing or halogen free flame retardants        such as bromine or phosphorus based monomers or resins;    -   5. 5-40 wt % filler combination (two or more fillers combined)        of the following possibilities: fused silica, crystalline        silica, fumed silica, talc, clay, core shell rubber particles or        particulate flame retardants.

In yet another aspect, this invention includes resins having thefollowing ingredients were the weight percent amounts are reporting on atotal weight basis including solvent(s):

-   -   1. 30%-40% solvent package of low and high boiling solvent:        methyl ethyl ketone, cyclohexanone;    -   2. 15%-30% Styrene maleic anhydride co-polymer (SMA)    -   3. 10%-20% Epoxy—combination of brominated or non-brominated        epoxy;    -   4. 0.5%-10% Tetrabromobisphenol A or tetra-DOPO-bisphenol A;    -   5. 5%-12.5% Talc    -   6. 5%-25% Fused silica    -   7. 0.01%-0.03% Tinopal OB (UV blocker) (optional)    -   8. 0.01-0.13% Tetrabutylphosphonium acid acetate (TBPAAc),        2-methylimidazole (2-MI), or 2-phenylimidiazole (2-PI).        Solvents

One or more solvents are typically incorporated into the resincompositions of this invention in order to solubilize the appropriateresin composition ingredients, and/or to control resin viscosity, and/orin order to maintain the ingredients in a suspended dispersion. Anysolvent known by one of skill in the art to be useful in conjunctionwith thermosetting resin systems can be used. Particularly usefulsolvents include methyl ethyl ketone (MEK), toluene, dimethylformamide(DMF), acetone, propyl acetate, cyclohexanone and combinations thereof.

When used, solvents are present in the resin in an amount of from about20 wt % to about 50 wt % as a weight percentage of the total weight ofthe solvent-containing resin composition. A useful solvent is acombination of a low and high boiling point solvent such as methyl ethylketone and cyclohexane.

Optional Ingredients

(a) Tougheners

The thermosetting resin compositions of this invention may include oneor more tougheners. The tougheners are added to the resin compositionsto improve the drilling performance of the resulting composites andlaminates. Useful tougheners include methylmethacrylate/butadiene/styrene copolymer, methacrylate butadiene styrenecore shell particles, and mixtures thereof. A preferred toughener ismethacrylate butadiene styrene core shell particles, which is availablefrom Rohm & Haas (100 Independence Mall West, Philadelphia, PA) underthe trade name Paraloid®. When used, tougheners are present in thethermosetting resin compositions of this invention in an amount fromabout 1% to about 5%, preferably from about 2 to about 4%, based on 100%by weight solids of the composition.

(b) Other Optional Ingredients

Optionally, the compounded resin may also contain other additives suchas defoaming agents, leveling agents, dyes, and pigments. For example, afluorescent dye can be added to the resin composition in a trace amountto cause a laminate prepared therefrom to fluoresce when exposed tolight with optical inspection equipment. A useful fluorescent dye is ahighly conjugated diene dye. One example of such a dye is UVITEX® OB(2,5-thiophenediylbis(5-tert-butyl-1,3-benzoxazole), available from CibaSpecialty Chemicals, Tarrytown, New York.

Other optional ingredients known by persons of skill in the art to beuseful in resins that are used to manufacture printed circuit boardlaminates may also be included in the resin compositions of thisinvention.

The prepregs and laminates of this invention made with resin systemsincluding a combination of fumed silica and talc synergistically exhibitlower expansion under thermal stress and reflow which is especially thecase as the quantity of styrene increases in ratio to the anhydride inthe SMA. This expansion improvement caused by the combination of fillersimproves even more with increasing SMA steric to anhydride ratios withanhydride to styrene ratios of 1:1; 1:2; 1:3; 1:4; 1:5; 1:6, 1:7, 1:8,and 1:9 being especially useful.

In another aspect of this invention, the resins can include differentratios of SMA's and different combinations of SMA's. For instance, acombination that would include having two or more of the anhydride tostyrene ratios, 1:3, 1:4, 1:5, 1:6, together with the talc and fumedsilica combined filler may be used. Extensions of these fillercombinations include any filler type similar to talc that is composed ofplatelets in combination with spherical or oblong or even porous shapedsilica fillers. This would include a combination of any of these shapedfiller such as a shell rubber core particle that is generally spherical.Resins including such a filler combination are more homogenous therebyimproving thermal properties that are specific to laminates and prepregmaterials used in the PCB industry. The industry has a long history ofthermal requirements that help to prevent any delamination of thelaminates inside a printed circuit boards. The resins including thecombination of fillers disclosed above when incorporated into laminatesthat are used in PCB's prevent PCB delamination in addition to reducinglaminate expansion under thermal stress.

The combination of resin ingredients—including the two differentfillers—produces a product that exhibits increased expansion as theratio of the steric bulk is greater in the SMA system. This greaterratio is desirable for low dielectric constant properties, but with thisadvantage there comes an increase of expansion and thermal instabilitythat has been solved in most recent history by the use of silica filleralone. The combination of two fillers in the resins described hereinhelp decrease expansion and thermal stability especially under thermalstress and reflow and decrease the threat of delamination and/or whiteglass crazing and/or wicking.

Prepregs and Laminates

The resins described above are useful for preparing prepregs and/orlaminates used in the manufacture of printed circuit boards. In order tobe useful in manufacturing printed circuit boards the laminates can bepartially cured or B-staged (in which instance they are referred to asprepregs) in which state they can be laid up with additional materialsheets and fully cured (“C-staged”) to form a layup or PCB.Alternatively, the resins can incorporated into C-staged laminatesheets, resin coated copper sheets or interlayer sheets.

In one useful method, the resin is used to manufacture prepregs in abatch or in a continuous process. Prepregs are generally manufacturedusing a reinforcing material such a woven glass web (fabric) which isunwound into a series of drive rolls. The web is then conveyed to acoating area where the web is immersed in a tank containing thethermosetting resin including solvent at which point the glass webbecomes saturated with the resin. The resin saturated glass web is thenpassed through a pair of metering bars or rolls to remove excess resinfrom the saturated glass web and thereafter, the resin coated webtravels the length of a drying tower for a selected period of time untilthe solvent is evaporated from the web. Optional second and subsequentcoatings of resin can be applied to the web by repeating these stepsuntil the preparation of the prepreg is complete whereupon the prepregis wound. The woven glass web can be substituted with a woven fabricmaterial, paper, plastic sheets, felt, and/or particulate materials suchas glass fiber particles or particulate materials.

In another process for manufacturing prepreg or laminate materials,thermosetting resins of this invention are premixed in a mixing vesselunder ambient temperature and pressure. The viscosity of the pre-mix is˜600-1000 cps and can be adjusted by adding or removing solvent from theresin. Fabric substrate (typically but not limited to E glass) is pulledthrough a dip tank including the premixed resin, through an oven towerwhere excess solvent is driven off and the prepreg is rolled or sheetedto size, layed up between Cu foil in various constructions depending onglass weave style, resin content & thickness requirements.

The thermosetting resin (resin) mix can also be applied in a thin layerto a Cu foil substrate (RCC—resin coated Cu) using slot-die or otherrelated coating techniques.

The prepregs, laminates, resin coated copper foils and like, all madeusing resins described herein are useful in manufacturing printedcircuit boards (PCBs) using manufacturing techniques that are well knownin the art.

EXAMPLES

Resins were prepared having a single talc filler (ISE-S4) and having afiller including silica and talc (ISE-S3) according to the formulationbelow. The resins were used to prepare prepregs and laminates includingresin impregnated glass fabrics of the same type. The prepregs andlaminates were then used to prepare a 24 layer multi-layer printedcircuit test boards having the specifications set forth in Table 3 belowand subsequently tested for many properties including their ability towithstand delamination, their ability to withstand wicking and theirability to withstand white glass crazing.

ISE-S3-24L stack-up ISE-S4-24L stack-up 1 oZ Cu 1 oZ Cu L1 1 × 2116RC58.1% L1 1 × 2116 RC57.8% L2 4 mil [2 × 106] H/H L2 4 mil [2 × 106]H/H L3 1 × 2116 RC58.1% L3 1 × 2116 RC57.8% L4 4 mil [2 × 106] H/H L4 4mil [2 × 106] H/H L5 1 × 2116 RC58.1% L5 1 × 2116 RC57.8% L6 4 mil [2 ×106] H/H L6 4 mil [2 × 106] H/H L7 1 × 2116 RC58.1% L7 1 × 2116 RC57.8%L8 5 mil [1 × 2116] 1/1 L8 5 mil [1 × 2116] 1/1 L9 2 × 1080 RC69% L9 2 ×1080 RC68.7% L10 4 mil [2 × 106] 2/2 L10 4 mil [2 × 106] 2/2 L11 2 ×1080 RC69% L11 2 × 1080 RC68.7% L12 5 mil [1 × 2116] 1/1 L12 5 mil [1 ×2116] 1/1 L13 2 × 1080 RC69% L13 2 × 1080 RC68.7% L14 4 mil [2 × 106]2/2 L14 4 mil [2 × 106] 2/2 L15 2 × 1080 RC69% L15 2 × 1080 RC68.7% L165 mil [1 × 2116] 1/1 L16 5 mil [1 × 2116] 1/1 L17 1 × 2116 RC58.1% L17 1× 2116 RC57.8% L18 4 mil [2 × 106] H/H L18 4 mil [2 × 106] H/H L191*2116 RC58.1% L19 1 × 2116 RC57.8% L20 4 mil [2 × 106] H/H L20 4 mil [2× 106] H/H L21 1 × 2116 RC58.1% L21 1 × 2116 RC57.8% L22 4 mil [2 × 106]H/H L22 4 mil [2 × 106] H/H L23 1 × × 2116 RC58.1% L23 1 × 2116 RC57.8%L24 1 oZ Cu L24 1 oZ Cu

In Table 3, 1×2116RC57.8% refers for example to a prepreg having 1-plylayer of 2116 woven glass having a resin content (RC) of 57.8%. 4mil[2×106]H/H refers to a fully cured 4 mm laminate made from two resincoated layers of 106 glass cloth. In addition to the two resins listedabove, IS415, a commercially available SMA/epoxy resin prepreg (withoutany fillers) was also used in preparing a test boards as described inTable 3 above.

The ISE-S3 resin had the formula set forth in Table 4 below.

TABLE 4 Resin Formula- Component Chemical Name (parts by weight) Styrenemaleic anhydride SMA 17.6 co-polymer Epoxy resin Bisphenol A 10.3 Epoxyresin Brominated Bisphenol A 11.1 Cross-Linking AgentTetrabromobisphenol A 5.6 Filler Silated Talc 5.8 Filler Amorphous fusedsilica (silated) 5.8 Solvent MEK 26.8 Solvent Cyclohexanone 15.2Catalyst Tetrabuylphosphonium acid 0.1 acetateIncludes optional Paraloid—1.7 wt %UV Blocker—0.02 wt %

The printed circuit board tested was a test vehicle including:

-   -   Multiple pitch dimensions and BGA designs;    -   24 L and approximately 3 mm thick with 4 layers of 2 ounce        copper;    -   Resin contents adjusted based on density of the two variants and        targeted to maintain same volume of resin;

The ISE-S4 resin had a similar formula but used all talc (11.6 wt %).

The IS415 resin had a similar formula but omitted fillers altogether.

The testing results of on the test vehicle indicated that:

-   -   Both ISE-S3 and ISE-S4 performed well in terms of thermal        performance after 6×260° C. IR reflow.        However, ISE-S3 performed better than ISE-S4 in several        important areas. ISE-S3 had:    -   Greater resistance to delamination    -   Less white glass/crazing    -   Higher Tg at T288    -   ISE-S4 exhibited Interconnect Defects ICD's while ISE-S3 did        not.

The results of the mechanical, thermal and electrical test performed oneach of the three test boards are set forth in the Tables 5-7 below.

TABLE 5 IS415 ISE-S3 ISE-S4 RESULTS SUMMARY 24L 24L 24L Test Test MethodDescription Units board board board THERMAL DSC Tg IPC-TM-650 Scan 1 °C. 180.7 175.4 153.7 2.4.25 Scan 2 ° C. 183.4 177.4 162.8 Delta Tg ° C.2.7 2.0 9.1 TMA IPC-TM-650 Tg ° C. 176.0 169.7 155.1 (Tg and z- 2.4.24Initial Thickness mm 3.2320 2.8850 3.2074 CTE) z-CTE Pre-TG ppm/° C.78.6 71.0 68.1 z-CTE Post-Tg ppm/° C. 374.4 323.5 320.6 Expansion(50-260° C.) % 4.2 3.8 4.0 Expansion (50-288° C.) % 5.3 4.6 4.9 Td ° C.— — — T-260 IPC-TM-650 Clad min 6.8 >60 >60 2.4.24.1 Unclad min — — —T-288 IPC-TM-650 Clad min 0.7 7.5 2.0 2.4.24.1 Unclad min — — — TGA TdIPC-TM-650 0.5% wt loss ° C. 323.4 331.6 336.5 2.4.24.6 1.0% wt loss °C. 334.7 342.0 343.8 1.5% wt loss ° C. 339.7 345.8 346.5 2.0% wt loss °C. 342.6 348.1 348.2 2.5% wt loss ° C. 344.6 349.9 349.5 3.0% wt loss °C. 346.0 351.3 350.5 3.5% wt loss ° C. 347.0 352.5 351.5 4.0% wt loss °C. 347.9 353.6 352.4 4.5% wt loss ° C. 348.7 354.5 353.2 5.0% wt loss °C. 349.4 355.4 354.0 DMA Tg IPC-TM-650 1st Scan (Tan Delta) ° C. 199.3200.7 190.6 2.4.24.4 2nd Scan (Tan Delta) ° C. 197.5 207.5 193.4 DeltaTg (Tan Delta) ° C. −1.8 6.8 2.8 DMA Modulus IPC-TM-650 Storage Modulus@ 50° C. MPa 10,453 13,070 12,256 (internal 2.4.24.4 (1st scan TanDelta) reference Storage Modulus @ 100° C. MPa 10,316 12,870 12,018only) (1st scan Tan Delta) Storage Modulus @ 150° C. MPa 9,858 12,16010,448 (1st scan Tan Delta) Storage Modulus @ 200° C. MPa 2,176 4,0251,529 (1st scan Tan Delta) Storage Modulus @ 250° C. MPa 915 2,018 1,103(1st scan Tan Delta)

TABLE 6 RESULTS SUMMARY IS415 ISE-S3 ISE-S4 Test 24L 24L 24L Test MethodDescription Units board board board DIMENSIONAL/MICRO X-sectionIPC-TM-650 White Glass um 137 116 264 IR reflow 6 × 260° C.- 2.1.1Wicking um 33 36 44 1.0 mm BGA back- ICD (of interconnects No./No. No NoNo drill inspected) interconnect interconnect interconnect X-sectionIPC-TM-650 White Glass um 186 100 240 IR reflow 6 × 260° C.- 2.1.1Wicking um 47 32 47 1.0 mm BGA ICD (of interconnects No./No. No No Noinspected) interconnect interconnect interconnect X-section IPC-TM-650White Glass um 193 104 201 IR reflow 6 × 260° C.- 2.1.1 Wicking um 43 3641 0.8 mm BGA ICD (of interconnects No./No. No No No inspected)interconnect interconnect interconnect X-section IPC-TM-650 White Glassum 160 97 223 IR reflow 6 × 260° C.- 2.1.1 Wicking um 51 40 46 1.0 mmBGA ICD (of interconnects No./No. 0/280 0/280 0/280 (reference)inspected) X-section IPC-TM-650 White Glass um 214 99 262 IR reflow 6 ×260° C.- 2.1.1 Wicking um 39 40 47 0.8 mm BGA ICD (of interconnectsNo./No. 0/200 0/200 0/200 (reference) inspected)

TABLE 7 RESULTS SUMMARY IS415 ISE-S3 ISE-S4 Test 24L 24L 24L Test MethodDescription Units PCB PCB PCB DIMENSIONAL/MICRO X-section IPC-TM-650White Glass um 151 70 154 IR reflow 6 × 260° C.- 2.1.1 Wicking um 51 3143 thermal via 1.0 mm ICD (of interconnects No./No. 0/360 0/360 0/360(with soldermask) inspected) X-section IPC-TM-650 White Glass um 170 109135 IR reflow 6 × 260° C.- 2.1.1 Wicking um 41 36 42 thermal via 0.8 mmICD (of interconnects No./No. 0/360 0/360 0/360 (with soldermask)inspected) X-section IPC-TM-650 White Glass um 132 92 136 IR reflow 6 ×260° C.- 2.1.1 Wicking um 40 30 40 thermal via 0.65 mm ICD (ofinterconnects No./No. 0/396 0/396 4/396 (with soldermask) inspected)X-section IPC-TM-650 White Glass um 153 57 167 IR reflow 6 × 260° C.-2.1.1 Wicking um 35 25 37 thermal via 0.5 mm ICD (of interconnectsNo./No. 0/660 0/660 18/660 (with soldermask) inspected) X-sectionIPC-TM-650 White Glass um 163 91 139 IR reflow 6 × 260° C.- 2.1.1Wicking um 28 30 39 thermal via 1.0 mm ICD (of interconnects No./No.0/360 0/360 5/360 inspected) X-section IPC-TM-650 White Glass um 125 90153 IR reflow 6 × 260° C.- 2.1.1 Wicking um 30 31 44 thermal via 0.8 mmICD (of interconnects No./No. 0/360 0/360 2/360 inspected) X-sectionIPC-TM-650 White Glass um 139 105 148 IR reflow 6 × 260° C.- 2.1.1Wicking um 37 36 38 thermal via 0.65 mm ICD (of interconnects No./No.0/396 0/396 2/396 inspected) X-section IPC-TM-650 White Glass um 121 124178 IR reflow 6 × 260° C.- 2.1.1 Wicking um 30 25 41 thermal via 0.5 mmICD (of interconnects No./No. 0/660 0/660 10/660 inspected)Tables 6-7 detail the results of IR reflow tests at 260 degreescentigrade. The IR reflow tests (infrared reflow soldering) of vias andball grid arrays. The reflow tests indicate that the boards made withthe ISE-S3 prepregs and laminates exhibited wicking and white glasscrazing results that were consistently better than the boards made withIS415 and ISE-S4 prepregs and laminates.

It should be noted that wicking is a measure of the distance coppermigrates into glass bundles adjacent to plated through holes. Further,“crazing” or “white glass” as it is referred to in the tables aboverefers to the amount (distance) of separation between the epoxy systemand individual glass fibers. When viewed with a microscope in across-section, crazing produces a silver or white sheen running downindividual glass fibers. The silver sheen is created by the air gaparound the individual glass fibers reflecting light

In addition, the boards were cut open and viewed in cross-section afterthe 6×IR reflow 260° C. testing and visually examined for delamination,i.e. areas where adjacent prepreg or laminate layers have separated. Thevisual results are reported in Table 8 below.

TABLE 8 Delamination Examination Results Board Type IS415 ISE-S3 ISE-S41.0 mm BGA Yes delamination None None (Backdrill cupon) 1.0 mm BGA Yesdelamination None None 0.8 mm BGA Yes delamination None Yes delamination0.8 mmBGA Yes delamination None Yes delamination (reference) 1.0 mmThermal Via Yes delamination None None (with soldermask) 0.8 mm ThermalVia Yes delamination None None (with soldermask) 1.0 mm Thermal Via Yesdelamination None None 0.8 mm Thermal Via Yes delamination None None 0.6mm Thermal Via Yes delamination None Yes delamination BGA = Ball GridArrayThe results from Table 8 above demonstrate that the boards made withlaminates including the silica/talc filler combination exhibited nodelamination after reflow tests in BGA and thermal via applications.

Having described resins and articles containing resins in detail aboveand by reference to specific examples thereof above, it will be apparentthat modifications and variations are possible without departing fromthe scope of the disclosure defined in the appended claims. Morespecifically, although some aspects of the present disclosure areidentified herein as particularly advantageous, it is contemplated thatthe present invention is not necessarily limited to these particularaspects of the disclosure.

What is claimed is:
 1. A resin composition comprising: styrene maleicanhydride co-polymer; at least one epoxy resin; at least onecross-linking agent; talc present in the resin in an amount ranging frombout 2.5 to about 15 wt % on a dry basis; and silica present in theresin in an amount ranging from about 2.5 to about 25 wt % on a drybasis; wherein the weight ratio of silica to talc is in the range fromabout 1:2.5 to about 5:1.
 2. The resin of claim 1 wherein the silica isfused silica.
 3. The resin of claim 1 wherein the silica is a silatedsilica.
 4. The resin of claim 1 wherein the talc is a silated talc. 5.The resin of claim 1 including from about 5 to about 12.5 wt % talc andfrom about 5 to about 25 wt % of silated fused silica each on a dryweight basis.
 6. The resin of claim 1 wherein the styrene maleicanhydride co-polymer is present in the resin in an amount ranging fromabout 5 to about 40 wt % on a dry solvent free resin basis.
 7. The resinof claim 1 wherein the at least one epoxy resin is present in the resinin an amount ranging from about 10 to about 50 wt % on a dry solventfree resin basis.
 8. The resin of claim 1 wherein the at least one epoxyresin is selected from a brominated bisphenol A, a brominated bisphenolF, a non-brominated bisphenol A, a non-brominated bisphenol F andcombinations thereof.
 9. The resin of claim 1 wherein the at least onecross-linking agent is present in the resin in an amount ranging fromgreater than 0 to about 20 wt % on a dry solvent free resin basis. 10.The resin of claim 1 wherein the at least one cross-linking agent isselected from tetrabromobisphenol A, tetra-DOPO-bisphenol A or a mixturethereof.
 11. The resin of claim 1 including from about 0.01 to about 3.0wt5 on a dry solvent free resin basis of at least one azo-type catalyst.12. The resin of claim 1 including a catalyst selected fromazobisisobutyronitrile, 2-propyl imidiazole, tetrabutylphophonium acidacetate, 2-methylimidazole and combinations thereof.
 13. A resincomposition comprising: from about 15 to about 35 wt % on a dry solventfree resin basis of a styrene maleic anhydride co-polymer; from about 5to about 45 wt % on a dry solvent free resin basis of at least one epoxyresin selected from a brominated bisphenol A epoxy resin, a brominatedbisphenol F epoxy resin, a non-brominated bisphenol A epoxy resin, anon-brominated bisphenol F epoxy resin or a combinations thereof; fromabout greater than 0.5 to about 10 wt % on a dry solvent free resinbasis of at least one cross-linking agent selected fromtetrabromobisphenol A, tetra-DOPO-bisphenol A and mixtures thereof; fromabout 2.5 to about 12.5 wt % on a dry resin basis of talc; and fromabout 2.5 to about 12.5 wt % on a dry resin basis of fumed silica. 14.The resin composition of claim 13 wherein the weight ratio of fumedsilica to talc ranges from 1:2.5 to 5:1.
 15. The resin composition ofclaim 13 wherein the weight ratio of fumed silica to talc ranges from1:1 to 2.5:1.
 16. The resin composition of claim 15 wherein the fumedsilica is an amorphous silated fumed silica.
 17. The resin compositionof claim 13 wherein the talc is silated talc.